The feasibility of using less than optimally prepared tissues for electron microscopic study has been adequately demonstrated. Use of such materials permits not only retrospective studies to be carried out on accumulated materials but also permits the examination of rarities. Combining the techniques of transmission (including histochemistry) electron microscopy with scanning (including X-ray probe microanalysis as well as histochemistry) electron microscopy permits further study of a number of disease entities using routinely fixed material accumulated in the Registry of Ophthalmic Pathology. Studies are ongoing as well in a number of disease entities (e.g. Meesmann's epithelial dystrophy of the cornea, Reia-Bucklers' dystrophy of the cornea, etc.) both optimally and suboptimally prepared for electron microscopic examination. BIBLIOGRAPHIC REFERENCES: Cursino, J. W. and Fine, B. S.: A histologic study of calcific and noncalcific band keratopathies. Am. J. Ophthalmol. 82:395-404, 1976. Tso, M. O. M. and Fine, B. S.: Electron microscopic study of human papilledema. Am. J. Ophthalmol. 82:424-434, 1976.